The framework of the geodesic dome is a network of interconnected struts which are commonly connected to form a framework which appears as a network of triangles so arranged that each side of each triangle abuts a side of an adjacent triangle, the abutting sides being of equal lenth. It is inherent in this network of triangles that each vertex of each triangle meets the vertices of several other triangles. The struts meeting at a common vertex point in the framework must be anchored and various means have been used to accomplish the anchoring. These means range from simply nailing the struts together at the common vertex point to providing connector units which hold the struts together rigidly at the common vertex.
A connector unit for this purpose was developed by Robert C. Liu, an agricultural engineer with the Department of Agriculture and is described in United States Department of Agriculture Miscellaneous Publications No. 1211 which was issued in October 1971.